Direct-current stabilized power supply device

• US 20060273777A1
• Filed: 06/02/2006
• Published: 12/07/2006
• Est. Priority Date: 06/02/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Suzuki, Tomohiro
• Granted Patent: US 7,545,609 B2
• Time in Patent Office: Days
• US Class Current: 323/312
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

In a direct-current stabilized power supply device provided with an output transistor that receives an input voltage from the outside and a control circuit that controls the output transistor so that an output voltage of the direct-current stabilized power supply device is stabilized, there is provided a voltage supply circuit that steps down the input voltage and outputs the voltage thus obtained as a voltage for driving the control circuit. The voltage supply circuit is built as a charge pump circuit that steps down the input voltage and then outputs the voltage thus obtained.

Claims

1. A direct-current stabilized power supply device, comprising:

an output element that receives an input voltage from outside; and

a control circuit that controls the output element so that an output voltage of the direct-current stabilized power supply device is stabilized,

the direct-current stabilized power supply device, further comprising;

a voltage supply circuit that steps down the input voltage and outputs the voltage thus obtained as a voltage for driving the control circuit,

wherein the voltage supply circuit is built as a charge pump circuit that steps down the input voltage and then outputs the voltage thus obtained.

2. The direct-current stabilized power supply device of claim 1, further comprising:

an output current detection circuit that detects a magnitude of an output current of the direct-current stabilized power supply device,

wherein the voltage supply circuit varies an amount of suppliable current of the charge pump circuit depending on the detected magnitude of the output current.

3. The direct-current stabilized power supply device of claim 1,

wherein the output element is a bipolar transistor,

wherein the direct-current stabilized power supply device further comprises a base current detection circuit that detects a magnitude of a base current of the bipolar transistor, and

wherein the voltage supply circuit varies an amount of suppliable current of the charge pump circuit depending on the detected magnitude of the base current.

4. The direct-current stabilized power supply device of claim 1,

wherein a load of the direct-current stabilized power supply device operates in a plurality of operating states of different electric power consumption, and

wherein the voltage supply circuit varies an amount of suppliable current of the charge pump circuit depending on an external signal indicating an operating state of the load.

5. The direct-current stabilized power supply device of claim 2,

wherein the charge pump circuit includes

a plurality of switching elements connected in series, and

a drive circuit that controls on/off of each of the plurality of switching elements,

wherein the charge pump circuit is configured so that the amount of suppliable current of the charge pump circuit increases with an increase in a ratio of an on-period of part of the plurality of switching elements to a sum of on and off periods, and

wherein the drive circuit varies the amount of suppliable current of the charge pump circuit by varying the ratio of the on-period of the part of the plurality of switching elements to the sum of the on and off periods.

6. The direct-current stabilized power supply device of claim 3,

wherein the charge pump circuit includes

a plurality of switching elements connected in series, and

a drive circuit that controls on/off of each of the plurality of switching elements,

wherein the charge pump circuit is configured so that the amount of suppliable current of the charge pump circuit increases with an increase in a ratio of an on-period of part of the plurality of switching elements to a sum of on and off periods, and

wherein the drive circuit varies the amount of suppliable current of the charge pump circuit by varying the ratio of the on-period of the part of the plurality of switching elements to the sum of the on and off periods.

7. The direct-current stabilized power supply device of claim 4,

wherein the charge pump circuit includes

a plurality of switching elements connected in series, and

a drive circuit that controls on/off of each of the plurality of switching elements,

wherein the charge pump circuit is configured so that the amount of suppliable current of the charge pump circuit increases with an increase in a ratio of an on-period of part of the plurality of switching elements to a sum of on and off periods, and

wherein the drive circuit varies the amount of suppliable current of the charge pump circuit by varying the ratio of the on-period of the part of the plurality of switching elements to the sum of the on and off periods.

8. The direct-current stabilized power supply device of claim 1, further comprising:

an output current detection circuit that detects a magnitude of an output current of the direct-current stabilized power supply device,

wherein, when the detected magnitude of the output current is found to be equal to or smaller than a predetermined first threshold value, the voltage supply circuit feeds the voltage obtained by stepping down the input voltage to a load of the direct-current stabilized power supply device, and supply of voltage from the voltage supply circuit to the control circuit is interrupted.

9. The direct-current stabilized power supply device of claim 1,

wherein the output element is a bipolar transistor,

wherein the direct-current stabilized power supply device further comprises a base current detection circuit that detects a magnitude of a base current of the bipolar transistor, and

wherein, when the detected magnitude of the base current is found to be equal to or smaller than a predetermined second threshold value, the voltage supply circuit feeds the voltage obtained by stepping down the input voltage to a load of the direct-current stabilized power supply device, and supply of voltage from the voltage supply circuit to the control circuit is interrupted.

10. The direct-current stabilized power supply device of claim 1,

wherein operating states of a load of the direct-current stabilized power supply device include a first operating state and a second operating state in which electric power consumption is lower than that required in the first operating state, and

wherein, when an external signal indicating an operating state of the load indicates the second operating state, the voltage supply circuit feeds the voltage obtained by stepping down the input voltage to the load of the direct-current stabilized power supply device, and supply of voltage from the voltage supply circuit to the control circuit is interrupted.

11. The direct-current stabilized power supply device of claim 1,

wherein the direct-current stabilized power supply device is a chopper-type direct-current stabilized power supply device.